Geochemical parameters influencing tungsten mobility in soils

Area of Science:

• Environmental Science
• Geochemistry
• Toxicology

Background:

• Tungsten biogeochemistry and mobility are gaining attention due to potential health impacts, including cancer clusters.
• Tungsten exists as soluble tungstate anions but can form polymers with variable properties.

Purpose of the Study:

• To determine geochemical parameters for tungstate species in a model soil.
• To understand the potential for tungsten mobility and how speciation affects it over time.

Main Methods:

• Spiking a model soil with metallic tungsten.
• Leaching soluble tungsten with deionized water over time.
• Determining partition coefficients for tungstate and polytungstate compounds.

Main Results:

• High equilibrium concentrations of soluble tungsten (>150 mg/L) were reached rapidly.
• Partition coefficients increased significantly (3-6 fold) over four months.
• This indicates a decrease in tungsten mobility as the soil ages.

Conclusions:

• Tungsten speciation in soil is dynamic and changes over time.
• These speciation changes directly impact tungsten's geochemical behavior and mobility.
• Aging of soil leads to reduced tungsten mobility, likely due to polymerization and altered speciation.